AntiPatterns: Refactoring Software, Architectures, and Projects in Crisis, a book by William J. Brown

I remember John Heintz piping up about this a few times during the Jay-Sea-Em-Es project. The "big ball of mud" is an antipattern where there is no real architecture and anything goes and the "lava flow" is antipattern in which things are easy to change at first, but then the lava cools to rock and it gets harder and harder to make changes.